1. Field of the Invention
The invention relates to a surface-discharge-type alternating-current plasma display panel, and more particularly, to structure of a partition wall defining discharge cells of the plasma display panel.
The present application claims priority from Japanese Application No. 2002-167074, the disclosures of which are incorporated herein by reference.
2. Description of the Related Art
FIGS. 11 and 13 schematically illustrate the cell structure of a surface-discharge-type alternating-current plasma display panel (hereinafter referred to as “PDP”) which has been proposed by the present applicant. FIG. 11 is a front view of the proposed PDP. FIG. 12 is a sectional view taken along the V—V line in FIG. 11, and FIG. 13 is a sectional view taken along the W—W line in FIG. 11.
The PDP in FIGS. 11 to 13 includes a front glass substrate 1 having a back surface on which a plurality of row electrode pairs (X, Y) are regularly arranged in the column direction and each extends in the row direction to form a display line L, and the row electrode pairs (X, Y) are covered by a dielectric layer 2, and then the dielectric layer 2 is covered by a protective layer 3.
The front glass substrate 1 is opposite to a back glass substrate 4 with a discharge space S in between, and on the opposing face of the back glass substrate 4, a plurality of column electrodes D are regularly arranged in the row direction and each extends in the column direction to form discharge cells C in the discharge space S at the respective intersections with the row electrode pairs (X, Y).
A partition wall 5 is shaped in a grid pattern by vertical walls 5A each extending in the column direction and transverse walls 5B each extending in the row direction. The partition wall 5 is provided between the front glass substrate 1 and the back glass substrate 4 to partition the discharge space S defined between them into the discharge cells C in the row and column directions. An additional dielectric layer 2A protrudes from a position opposite the transverse wall 5B of the partition wall 5 toward the back glass substrate 4 to come in contact with the corresponding partition wall 5 to close off the adjacent discharge cells C from each other in the column direction.
The discharge cells C have red (R)-, green (G)-, or blue (B)-colored phosphor layer 6 formed therein in turn and arranged in this order in the row direction.
For the generation of an image on the PDP, in an addressing period after completion of a reset period, an addressing discharge is selectively produced between one row electrode (the Y electrode in this example) in the row electrode pair (X, Y) and the column electrode D in each discharge cell C. As a result, the lighted cells (i.e. the discharge cells in which wall charges are generated on the dielectric layers 2) and the non-lighted cells (i.e. the discharge cells in which no wall charge is generated on the dielectric layer 2) are distributed over the panel surface.
In the sustaining discharge period after completion of the addressing discharge in the addressing period, a discharge-sustaining pulse is applied alternately to the row electrodes X and Y in the row electrode pair (X, Y) in each display line L. Thereby, a sustaining discharge is generated between the row electrodes X and Y in each lighted cell with every application of the discharge-sustaining pulse.
The sustaining discharge caused in the lighted cell generates ultraviolet light from a discharge gas sealed within the discharge space. The ultraviolet light excites the red-, green- or blue-colored phosphor layer 6 formed in the discharge cells C to emit visible light for the formation of the image to be displayed.
The partition wall 5 in the PDP has the capability of preventing the occurrence of a false discharge due to interference between discharges respectively generated in adjacent discharge cells C in the row direction and the column direction. For this reason, the partition wall 5 needs to have electrical insulation performance.
Such a partition wall 5 defining the discharge cells C of the PDP is conventionally formed by use of sand blasting techniques after the coating and burning of a low-melting glass paste, which disadvantageously increases manufacturing costs.
Hence, a measure proposed for reducing manufacturing costs while providing adequate electrical insulation performance in the partition wall 5 is that, as illustrated in FIG. 14, the inside of the partition wall 5 is formed of an electrically-conductive metallic base 5a, and the surface thereof is covered with a dielectric insulation layer 5b formed of a dielectric material having electrical insulation performance.
However, if the inside of the partition wall 5 is formed of the metallic base 5a in this way, as illustrated in FIG. 15, when a discharge-sustaining pulse is applied to the row electrodes X and Y in the sustaining discharge period, a potential difference is generated between the metallic base 5a of the partition wall 5 and the row electrode X or Y undergoing the application of the discharge-sustaining pulse (FIG. 15 illustrates the situation when the discharge-sustaining pulse is applied to the row electrode Y). This causes a part dc of the discharge current DC, which has to flow from the row electrode X to the row electrode Y, to flow toward the metallic base 5a of the partition wall 5 located in the proximity of the row electrode X, resulting in the problem of a decrease in the luminous efficiency caused by the sustaining discharge.
FIG. 15 also shows an electric field EF created in the discharge cell C when generating the sustaining discharge.